Your calibration is off. You need to calibrate each machine individually, you can't just plug in the theoretical steps/mm value and expect it to be exact.

1. Use a small square up against the carriage to place a pencil mark on your X axis beam.
2. Move the X carriage some convenient value, say 300mm, and make another pencil mark in exactly the same way. The larger the distance you move the carriage, the better the accuracy.
3. Use an accurate ruler (not a tape measure) to check the distance between the marks. Suppose it is 305mm. The formula for the correction is:

Commanded travel
---------------------------------- * Current setting (steps/mm) = New Setting (steps/mm)
Actual (measured) travel

Example:

300
------ * 800 = 0.9836 * 800 = 786.885
305

4. Put the corrected value (786.885) in your Steps/mm in your config file for that axis.
5. Repeat the steps above to verify that the axis now moves the distance expected. (note: with GRBL, you may need to Reset the controller before the new steps value is applied. Not sure with other controllers, like the Smoothieboard, but it can't hurt.)
6. Repeat for the other 2 axes.

MG

 

Quick Question with probably a long answer... If I have built my CBeam XL with Nema 2305 motors and xPro v2 board - standard 8 uStep, what is the max feed rate the machine can achieve for wood cutting. I realise it depends on the wood and size of tool etc but what is the logical maximum? Many posts on wood working have very high feed rates. Currently I have some CAM files set at about 1200mm/min. This appears to work ok but is slow and chips are not very big at all. I cant work out how fast the Nema motors can turn or at what speed they loose too much torque

 

If your using Mach3, you can see it in the Motor Tuning page. Check out: and use it as a general guide.

 

For a more detailed explanation check out the following video at the Half Way point to see just what is the capability of your stepper motors when they're tuned properly.
Until I had seen this video, I figured that I all I had to do was just use the Default Settings that Mach3 gave you when you used the Axis Calibration Method. How wrong I was.

 

So far I have only tried UGS (Classic and Platform versions) to send the grbl code and setup the machine.
I use Fusion360 to do the design and CAM. It will be for guitar building.
But interesting Glarc can get 2500mm/min - good to know. I will have a search for MACH3

 

Thats good. Would reduce the work time quite a bit. I assume DOC is depth Of Cut so "Step-down" in Fusion terms..? Is the single flute for better chip load? New to this and the "bigger chip" idea still feals counter intuitive ;-) Though I understand it in for cooling.

 

By using Onsruds Guide as a general rule, you should try upping your feed to around 2743.2mm/min with a Chip load: .004 to .006 and go from there.

 

I’ll hopefully have a play tomorrow to see how those speeds work at least as unloaded jogs initially. How does acceleration value relate to feed rate? Currently set at 100 I think from memory. Hopefully also try Mach3 demo and look at that speed calibration tool

Thanks again
Cliff

 

If you check out the following video, while it's for a Grizzly CNC Lathe. It explains Acceleration and how your machine should sound if you have the Acceleration is properly set up. You can go too far so you need to be very careful as you can defeat all the other the other settings that you've managed to correctly set.

 

Uhhh, Ronald, you forgot the link...

MG

 

Sorry about that, here it is:

 

Oh, that's the same one you put in farther up.

MG

 

Well I kept upping the X and y max and gave up around 4500mm/min as that maybe alot of stress on the machine stopping from that speed!!
In the end I think I settled on around 4000 for x and 3000 for Y. The y axis has alot of mass from the bed so thats why I left that lower.
The acceleration was a similar story. No signs of stalling or bad noises beyond 460.. I have settled at 400 as it seems responsive at that.
I think I left Z at 3000 and 400 too. Cuuting speeds will be adiferent story of course. Tride a test job but at a cutting height with a 1/2" cutter and tbh I think it will work better with a 12mm cut but at a lower speed. But its all part of the learning I suppose. I also ran a progran through without cutting to make sure the higher speeds in combination dont hurt anything. Seemed ok. But couldnt do alot of testing as the Stroom grbl post process is throwing alot of G3 errors. In the end I have gone back to the built in grbl processor procided by Fusion. Once I remove the "T1 M6" line they seem to work fine in the error checking at least. Thank for the tips above, they were very useful

 

Glad I could help, As far as your G3 problems, while I'm not using GRBL. Have you ever investigated Ferrite Cores added to your Motor and Power Cords? Check out the following video's and you'll understand what I'm referring to:

I depend like a lot of people on what CorvetteGuy50 has to say as he builds CNC Controllers for a living.

 

Sure is long winded. He could have said what was in that video in 3 minutes instead of 12.

I agree that ferrites help immensely, along with properly grounding the frame of the machine. You need a separate ground wire from each axis to the power supply, both for safety purposes and EMI reduction. I usually run one ground wire from each motor frame.

MG

 

Yeah, he sure is. But at least his information is dependable whereas a lot of the other information isn't.

 

Actually I did buy some ferrite rings when I bought all the switches etc. Havent fiutted them yet as the current wiring is a bit "temporary" while I understand it all and decide where to out my control box and pause-go-kill buttons etc. Having said that, so far I havent had any probelms with the limit switch wires event though they are just speaker wire...

Just run a first cut on higher speeds and seems with a 1/2" cutter I can comfortably do 6.5DOC at 2000.. may try 2500 as suggested above.
I initially forgot to set the DOC and so it was still 12.5mm!! It actaually almost worked but juddered somewaht at certain directions against the grain. 6,5mm seems to be fine.

 

Instead of the regular Limit Switches that most everyone else is using with either the Levers or the Induction Sensors. I'm going with Creltek Hall Effect Sensors available from Tindie.com which use a North Oriented Magnet and using them as Homing Switches only along with Soft Limits at the Opposite End. I chose them as they aren't susceptible to Cutting Fluids if I'm cutting Aluminum or Wood Dust. They also have a Breakout Board which uses RJ-11 Connectors to connect to your Breakout Board. Check out the following video to see what I mean.

 

Thanks for the Post Processor Lead, I've got a 3D Pinter Build Started and I was having trouble finding a post processor to use with my Arduino and Ramps 1.4 Driver Board.

 

Hi swarfer - I did try yours but I still get error 33s from that for many G3 moves - even with 4 decimal places set.

 

I tried the minimumChordLength or minimumCircularRadius to .5 and this didnt help.
Havent tried the allowedCircularPlanes setting so will give that a go.

What is the benefit of this Stroom/Swarfer processor?

 

Re the ferrite rings - Having just said "so far I havent had any probelms with the limit switch wires", I have just had a false hard limit error !!! It was about 80% through a longish program <sigh>. So will pop them onto the limit switch wires before I do any more!!. I assume they go just before the xPro controller board ?

I now need to find out
a) How do I cut down the postprocess file so I can continue from where it was...
b) how would I have correctly told it to continue. It said to "MSG RESET" but I couldnyt have done it right as I'm sure it altered the machine coordinates a bit. I'll post questions in a more suitable forum/topic.

 

I'd be spacing the Ferrite cores every 12 to 18 inches if possible and at the very least just before your Xpro controller board and just before the Limit Switches themselves. You can get ones that just clamp over the outside of the wire and as a side note, I'd be using shrink tubing on top of them to make sure they don't move.

As far as GRBL though you'll have to depend on the other members to assist you. GRBL is out of my league and looks 10 times harder than Mach3.

 

Mostly good info apart from the bit about soldering a crimped wire end.

Solder does not have ANY place in a compression fitting and the correct size end ferrules and the right crimp tool will compact wires into a low resistant connection. Adding solder to the mix is just adding a vector for the screw to come loose over time. I asked a few questions about why he adds solder on his youtube and mentioned fact NONE of the commercial CNC I have repaired add solder after crimping. He deleted my post as I think it made his PAINFULLY over priced cables look bad. For a single set you could get a good crimp tool and assortment of ferrules and have your whole controller looking pimp. Not wailing on his product but would rather see our members stock out their own tool kit than pay $$ for about 2 mins of work and a few bucks of parts....

 

You mentioned above about also earthing the frame of the CNC. Would this go to the earth tab of the switches and board?
Can I use one ead to the frame and use the frame as the earth for the limit switches? Then just one wire to the other terminals of the limit switches with ferrite rings on them.
As a side note I may replace y limit switches as I think they are giving me slightly variable home points. If I mark my start point with G28.1, it is not aways returning to exactly the same spot. Sometimes it does and sometimes not. I can only assume the arm of the switch is bending a different amount sometimes. So need some better quality switches.. or those hall effect things

 

Very interested in this as the XL width limit means I have to cut guitar bodies in two halves. I thought thos would be reltively easy with locatiing pins but its proving to cause ALOT of extra work and head scraching. AM I right thinking that all I need over the XL kit is 2 extra 1000mm C Beams and corresponding screw drive bars? ie use the existing Y plate assemblies to mount the two uprights.

 

Basically Yes, as My machine is 500 mm on the Y-Axis whereas it's 1000 mm on the X-Axis for all intents and purposes along with a lot of others.